Mineral concentrator and method of concentrating

ABSTRACT

Relatively heavy mineral or metal is rapidly and efficiently separated from lighter particulate material with which it is mixed. An aqueous slurry of the mixture is drawn through a series of hutches, the bottoms of consecutive hutches being disposed in ascending sawtooth arrangement. The heavier mineral settles to the bottom of the hutch, where an openable and closable discharge port is located, while the lighter material is carried to the next hutch. By connecting a surge tank to the bottom of the hutches and filling the entire unit with water, the hutches can be discharged without disrupting the separation process.

[4 1 Mar. 27, 1973 [54] MINERAL CONCENTRATOR AND METHOD OF CONCENTRATING [75] Inventor: Edwin C. Potter, .Brooklyn Park,

' Minn.

[73] Assignee: Marine Science Industries, Inc.,

Minneapolis, Minn.

22 Filed: June 8, 1971 21 Appl. No.: 150,995

[52] US. Cl ..209/156, 209/490 [51] Int. Cl. ..B03b 3/30 [58] Field of Search ..209/155, 156, 422, 461, 490,

3,683,945 8/1972 Weisser ..209/1S6 X FOREIGN PATENTS OR APPLlCATlONS 527,806 7/1956 Canada ..209/l56 Primary ExaminerFrank W. Lutter Assistant ExaminerRalph J. Hill Attorney-Richard E. Brink [57] ABSTRACT Relatively heavy mineral or metal is rapidly and efficiently separated from lighter particulate material with which it is mixed. An aqueous slurry of the mixture is drawn through a series of hutches, the bottoms of consecutive hutches being disposed in ascending sawtooth arrangement. The heavier mineral settles to the bottom of the hutch, where an openable and closable discharge port is located, while the lighter material is carried to the next hutch. By connecting a surge tank to the bottom of the hutches and filling the entire unit with water, the hutches can be discharged without disrupting the separation process.

10 Claims, 1 Drawing Figure MINERAL CONCENTRATOR AND METHOD OF CONCENTRATING BACKGROUND OF THE INVENTION This invention relates to gravity separators for concentrating ore or relatively heavy minerals admixed with less desirable lighter material.

Minerals such as gold, platinum, tin, chromium and iron frequently occur in combination with gravel, the deposit being termed a placer. Since these minerals are all heavier than the diluent gravel, it has long been known to use some type of washing procedure for effectingseparation; the minerals settle to the bottom, while the grave] is washed away. Although this process can be carried out by hand methods, it is more practical to use a sluice, riffle board, or similar equipment. There are many variations of such equipment, but all of them introduce an aqueous slurry of the mineral and gravel at the top of an inclined table having transverse strips, or riffles. The gravel flows over the top of the riffles, while the heavier mineral collects behind them.

The devices just described are intermittent in operation and'require considerable manual labor. As a result, attempts have been made to develop automatic and continuous modifications which utilize either the same or different principles. One such device, for example, is an open-ended rotating drum lined with rubbery corduroy-type riftling which .continuously picks up and discharges the concentrate into an internal launder. If possible, a turbulent flow is sought, so as to promote release of trapped particles. None of these devices, however, is economically feasible when either the concentration of mineral in the original deposit is extremely low or the particle size is extremely small.

Another type of equipment is the I-Iumphreys spiral concentrator, operating solely on gravity flow, but utilizing several turns of a conduit having a modified semicircular cross section. Washwater, supplied from a small channel paralleling the main channel, washes away fine gangue and other diluent particles. Although effective, this equipment is extremely expensive and bulky, making it impractical for use in concentrating large volumes of dilute mineral product.

SUMMARY The present invention provides a simple and relatively inexpensive way to continuously process large volumes of relatively low grade ore. Indeed, the invention makes it economically feasible to reprocess tailings resulting from previous separation methods. The equipment of the invention is susceptible to precise and delicate adjustment to achieve either complete removal of the desired mineral along with some impurity, or separation in which there is substantially no impurity remaining in the concentrate.

The equipment and process of the invention are likewise adaptable to a wide variety of feed material, ranging from placer mining operations to removal of lead shot from lake bottoms. In the former case, the invention proves useful in processing the tailings from other less efficient operations. In the latter case, the shot can be so cleanly separated from sand and other particulate diluent that it can be dried and, withoutfurther modification, used in the reloading of shotgun shells.

With the cooperation of conventional hydraulic dredging equipment, the machinery of the invention can be used in processing deposits of minerals on the beds of lakes, streams and shallow portions of the ocean. To illustrate, it is believed that the invention will be useful in the concentration of barite, or barytes (BaSO found in admixture with sand and crushed sea shells at the bottom of bodies of water such as Bering Sea.

In some respects the invention is based on a more sophisticated application of principles which have been employed in dredging operations for many years. A hydraulic dredge, for example, utilizes a drill to loosen a river bed, pumping the resultant slurry of silt and water to another barge, where the silt is collected and the water returned to the river. (Alternatively, of course, the slurry can be pumped onto marshy land to render it more usable.) Occasionally a relatively large rockwill be sucked up by the pipe on the river bottom; since this would damage the pump if it were not removed, it is customary to have a som'ewhat'enlarged chamber, or rock box on the barge, located between the feed pipe and the pump. The rocks fall to the bottom of these boxes and are removedfrom time to time.

The present invention utilizes equipment similar to the dredging equipment just described, except that the rock box" is replaced by a hutch-preferably a connected series of hutches-which provide for settling of the heavier mineral which it is desired to concentrate. Each hutch is a chamber having an input and an output on opposite walls, a sloping bottom extending upward from the input wall to the output. Provision is made for removing the concentrate without disrupting the continuity of the operation; this advantageous result is accomplished by connecting the bottoms of the hutches to a closed liquid-filled surge tank, into which the concentrate in the hutches can be discharged and from which the concentrate can be subsequently removed.

BRIEF DESCRIPTION OFTI-IE DRAWING Understanding of the invention will be facilitated by reference to the accompanying drawing, in which the single FIGURE depicts a longitudinal cross-sectional view of a concentrator made inaccordance with the in- I vention.

DESCRIPTION OF PRESENTLY PREFERRED EMBODIMENTS In the drawing, the concentrator comprises seriesconnected hutches 10, 20 and 30 mounted above surge tank 40. Feed line- 50 connects to h'utch 10, while tailings line 60 connects to hutch 30.

Each hutch 10, 20, 30 comprises a ceiling ll, 21, 31, a rear walll'2, 22, 32, a front wall 13,23, 33, and a sloping floor 14, 24, 34, at the rear (input) and lower end of which is concentrate discharge outlet 15, 25, 35.

Arranged forquickly opening or closing concentrate serves as feed inlet for hutch 30. Overflow opening 39 for hutch 30 leads to outlet line 55, as will be described more fully hereinbelow.

Beneath hutches 10, 20, 30 and an integral part of the preferred form of the concentrator is surge tank 40, having float valve air vents 41, 42, 43 at its highest points. Water line 44 is used to provide priming and makeup water in a manner which will be described subsequently, valve 45 being provided for control. Bleeder valve 46, located at the highest point'of the. concentrator (in the ceiling of one of the hutches) provides for" eliminating the last traces of air from the system.

Located at the bottom of surge tank 40 is concentrate discharge port 47, provided with gate 48, desirably having resilient neoprene face 48a to insure good sealing. Fluid cylinder 49 may be used to actuate gate 48. Located below surge tank 40 is concentrate funnel 70, through which all concentrate is ultimately transported. w 1

Input line 50 connects to inlet 18 in hutch and serves as the conduitfor introducing a slurry to be concentrated. In some instances it has been found desirable to provide for the introduction of an elutriating agent, e.g., Na PO,, into the feed line to assist in breaking up colloidal sludges and prevent clay from sticking to oppositely electrically charged metallic particles such as gold or platinum. This can be accomplished by aspirating an appropriate solution into input line 50 through line 51.

Centrifugal pump 52, located at the discharge and of theconcentrator unit, provides the vacuum which draws the feed slurry through the system, variable (which advantageously has about 20 slope), resting on gate 16. When a sufficient amount of concentrate has been accumulated, as may be determined through an observation port, gate 16 is opened, permitting the concentrate to fall into surge tank 40. Alternatively gate 16 may be arranged to open when a predetermined weight of concentrate rests upon it. Because surge tank 40 is also full of water, the system is not disturbed and no speed drive motor 53 permitting the adjustment of flow rates to effect the desired results. Vacuum gauget54 is mounted just upstream from pump 52, providing a simple way of determining the operatingco'nditions and duplicating results. Effluent containing water and tailings is discharged through outlet line 55 into tailings line 60 via pump 52. v

To operate the system, pump 52 is turned off, gate 48 closed, and gates 16, 26, 36 opened. Valve 45 is opened to permit the introduction of water (or other suitable liquid) through line 44 to fill surge tank 40 and hutches 10, 20, 30. Air escapes through vents 41, 42 and 43 until water fills the valves and they are sealed by their respective'floats. Bleeder valve 46 is then opened to insure removal of the last traces of air, after which valve is closed. Gates 16, 26, and 36 are then closed.

Input line 50 is then inserted into a source of slurrie'd particulate containing mineral which is to be concentrated and pump 52 started, its speed being adjusted to provide the desired degree of vacuum.

As feed slurry enters hutch 10, the solids content tends to drop, and if operating conditions are 'properly adjusted, the material having a higher specific gravity will strike sloping floor l4, slurry containing lighter particulate material and a lesser amount of heavier material being carried over to hutch 20 through overflow opening 19. The shape of hutch 20 establishes an eddy current in the slurry remaining therein, further inducing settling of the heavier mineral and washing away of the lighter particulate. The heavier mineral gradually slides or tumbles to the bottom of hutch l0 noticeable effect on continued separation and flow takes place. Gate 16 is then reclosed.

The manner of operation in hutches 20 and 30 is directly analogous to that in hutch l0 and need not be described.

When sufficient concentrate has collected at the bottom of surge tank 40, gate 48 is opened and the concentrate allowed to fall through collecting funnel into a suitable container. As gate 48 is opened, air enters the system, but it collects only in surge tank 40, since closed gates 16, 26, 36, keep it from entering hutches 10, 20, 30. Gate 48 is then closed and makeup water supplied through water line 44, forcing the air in surge tank 40 up and out through float valve vents 41, 42, 43, restoring the system to its original condition.

Surge tank 40 is, to the best of the inventors knowledge and belief, un iquein either concentrating or dredging equipment. As previously indicated, it performs the extremely valuable service of permitting continuous operation, completely avoidingthe introduction of air into the pump with consequent loss of prime and disruption of equilibrium operating conditions. It will nevertheless be appreciated that many of the advantages of the invention can be attained, especially for short runs, by merely utilizing the hutches. It is believed that there has never heretofore existed a concentrator with slope-bottomed hutches on the input side of the feed line, and it appears that unique results are attained.

With the benefit of the foregoing description, the

man skilled in the art will be able to make many adjustments to the system to achieve results suited to particular situations. Without in any way attempting to be exhaustive, butonly to illustrate the possibilities, it might be noted that high feed speed tends to provide for a purer concentrate than low speed, albeit with some loss of mineral via the effluent. 0n the other hand, if it is desired to retain all the mineral, even at the cost of less complete concentration, speed may be reduced. Cutting down the size of overflow openings 19, 29, 39 between adjacent hutches has the effect of increasing turbulence, improving the degree of separation, and making the size of this opening adjustable (as indicated in the drawing) permits another degree of control.

I claim:

l. A continuous concentrator for ore and the like,

b. below said hutch and integral therewith, a surge tank having a concentrate discharge port at the lower portion thereof, said concentrate discharge port being provided with an openable and closable gate;

c. supply means to provide slurry of liquid and feed material at said feed inlet opening; and

d. suction means to provide suction forward of said tailings outlet opening to draw said slurry into said feed inlet opening.

2. The concentrator of claim 1 wherein there are a plurality of hutches connected in series and the surge tank is connected to and integral with all of said hutches. v

3. The concentrator of claim 2 wherein a priming water line is connected to said surge tank.

4. The concentrator of claim 3 wherein an air bleeder vent is located at the top of the series of hutches and air bleeder vents are located at each high point in the surge tank.

5. The concentrator of claim 4 wherein the suction means is a variable speed centrifugal pump.

6 The concentrator of claim 5 wherein the size of the openings between hutches is adjustable.

7. The concentrator of claim 6 wherein each'of the gates can be quickly opened' or closed by actuating a fluid cylinder connected thereto.

8. A method of concentrating a relatively heavy particulate mineral which is intermixed with relatively lighter particulate material, comprising the steps of:

a. providing a series of connected hutches, each having a ceiling, a relatively short front wall, a relatively tall rear wall, and a floor sloping downwardly front to rear connecting the bottom of the rear wall to the bottom of the front wall, each of said hutches having an opening at the upper portion of both its front wall and its rear wall;

. supplying a slurry of liquid containing a mixture of said mineral and said material at the opening in the rear wall of the first hutch; and

c. applying suction at the opening in the front wall of the last hutch,

whereby said heavy mineral falls to the bottom of the hutches and said liquid and lighter material are discharged through said opening in the front wall ofthe last hutch.

9. The method of claim 8 wherein the liquid is water.

10. The method of claim 9 wherein the hutches are filled with water before supplying the slurry of mineral and lighter material to the first hutch. 

2. The concentrator of claim 1 wherein there are a plurality of hutches connected in series and the surge tank is connected to and integral with all of said hutches.
 3. The concentrator of claim 2 wherein a priming water line is connected to said surge tank.
 4. The concentrator of claim 3 wherein an air bleeder vent is located at the top of the series of hutches and air bleeder vents are located at each high point in the surge tank.
 5. The concentrator of claim 4 wherein the suction means is a variable speed centrifugal pump.
 6. The concentrator of claim 5 wherein the size of the openings between hutches is adjustable.
 7. The concentrator of claim 6 wherein each of the gates can be quickly opened or closed by actuating a fluid cylinder connected thereto.
 8. A method of concentrating a relatively heavy particulate mineral which is intermixed with relatively lighter particulate material, comprising the steps of: a. providing a series of connected hutches, each having a ceiling, a relatively short front wall, a relatively tall rear wall, and a floor sloping downwardly front to reAr connecting the bottom of the rear wall to the bottom of the front wall, each of said hutches having an opening at the upper portion of both its front wall and its rear wall; b. supplying a slurry of liquid containing a mixture of said mineral and said material at the opening in the rear wall of the first hutch; and c. applying suction at the opening in the front wall of the last hutch, whereby said heavy mineral falls to the bottom of the hutches and said liquid and lighter material are discharged through said opening in the front wall of the last hutch.
 9. The method of claim 8 wherein the liquid is water.
 10. The method of claim 9 wherein the hutches are filled with water before supplying the slurry of mineral and lighter material to the first hutch. 